1. Field of the Invention
The present invention relates to nonlinear, optical thin-films which can be used for optical devices such as an optical switch and an optical harmonic generator which make use of a nonlinear optical effect and a manufacturing method thereof.
2. Description of Related Art
A cut-off filter glass made by doping a semiconductor CdS.sub.x Se.sub.1-x in borosilicate glass is one of bulk nonlinear, optical materials, as described in for example J. Opt. Soc. Am. 73, 647(1983).
The cut-off filter glass is prepared by putting CdS.sub.x Se.sub.1-x and borosilicate glass material in a platinum crucible to melt them at a high temperature of about 1,600.degree. C.
However, the manufacturing method for a bulk nonlinear, optical material, as in case of manufacturing the cut-off filter glass, has the following problems: (a) The kind of a semiconductor to be doped is limited severely because the material needs to be melted at a high temperature. (A semiconductor having a low melting point will usually be evaporated, decomposed or oxidized.) (b) The amount of doping is limited. For example, it is difficult to disperse more than two to four weight percent of CdS.sub.x Se.sub.1-x in borosilicate glass. (c) In order to obtain fine particles, the melt is cooled rapidly and then the solid is subjected to thermal treatment. However, the control of the particle diameter is difficult because the particles grow randomly. (d) On manufacturing a nonlinear, optical device, it is necessary to form a thin film-like shape. However, it is difficult to form such a shape.